AK2571 Datasheet, PDF (27/52 Pages) Asahi Kasei Microsystems – Single-Chip Automatic Power/Temperature Control for WDM Laser Diodes

AKM Confidential
AK2571
5.3.2 Confirmation of other functions
1) OPALM confirmation
When the APC adjustments are complete, set R_OPALM_SET.
Gradually decrement the value of R_DACx OPALM is output as a current. Confirm LD light power is settled value or not
by monitoring the output of PDMON.
2) Aging Error Compensation confirmation
After APC adjustments are complete, write “1” in R_CTRL.Apc_fb. decrement the value of R_DACx , but don’t reduce it
too much as OPALM is output. APC Feedback begins to function and will increase the value of R_APC_CMPNST. In this
register access mode, APC does not add to R_DACx and the light power of the LD does not increase, actually. Eventually
R_APC_CMPNST will equal E_APC_FB_MAX. If E_CUALM_SET is set to an equal value of E_APC_FB_MAX
beforehand, CUALM out expresses the increment of aging compensation current.
3) Aging shift of wavelength compensation confirmation
This confirmation can be done with 2) Aging Error Compensation confirmation. R_CTRL.Atc_fb=”1” enables the ATC
feedback confirmation. Decrement the value of R_DACx, but do not reduce it too much as OPALM is output. APC
Feedback begins to function and increases the value of R_APC_CMPNST. According to this value, R_ATC_CMPNST is
increased by the E_ATC_FB_SET parameter. R_ATC_CMPNST will eventually equal E_ATC_FB_MAX. If
E_WLALM_SET is set equal to E_ATC_FB_MAX and below the value of E_APC_FB_SET or E_ATC_FB_SET
beforehand, WLALM output indicates the shift of target temperature.
6. Monitor function
6.1 AMON pin analog monitor
Set R_MON_SET (E_MON_SET) register, and monitor the values in the registers below through MON-DAC. Table 6-1
indicates the registers that can be monitored. Output voltage ( Vmon) (typ) is expressed below.
Vmon = (2.1-0.5) / 255*K+0.5 [V]
K=the decimal value of the register
Table 6-1 Monitoring Register
R_MON_SET
Monitoring Function
Remarks
0
0
0
0
Fixed voltage
0
0
0
1
PID control absolute value
0
0
1
0
APC feedback value
R_MON_DAC_FIX
R_RID_ABS[12:5]
R_APC_CMPNST[7:0]
0
0
1
1
ATC target value
R_TMPRT_CRNT[7:0]
0
1
0
0
ATC feedback value
0
1
0
1
IDAC1 set value
R_ATC_CMPNST[7:0]
R_DAC1[7:0]
0
1
1
0
IDAC2 set value
R_DAC2[7:0]
0
1
1
1
IDAC3 set value
R_DAC3[7:0]
1
0
0
0
T_V converter output
R_TV[7:0]
<Rev. 0.6E Preliminary>
-27-
2001/11